Genuine question. Can some wise person let me know why we aren't all using Veg oil in our diesel engines. I was reading that it actually produces a zero amount of CO2 because the amount it gives out is negated by the amount 'locked in' by the oil producing plants when they grow. I know it takes a bit more fiddling to stop it solidifying but then again things like electric/petrol hybrids are pretty fiddly too. I seem to recall that diesel's originally ran on coconut oil or something but I might have made that up. It would seem to be a solution to the whole pissing around in the Middle East to get oil thing too. Is it because we couldn't harvest enough oil? Petrol company conspiracy? Smells of chips?